1. Field of the Invention
The present invention provides mobile emission measurement with proportional sampling of vehicle raw exhaust to collect a number of different emissions or toxic compounds in the vehicle exhaust gas.
2. The Prior Art
A need has existed in the art for measurement of polycyclic aromatic hydrocarbons (“PAHs” and “nitro-PAHs”) from a vehicle during a transient test schedule. This data is needed to determine effects on health of exhaust components from engines run on gasoline and various ethanol blends.
A number of prior art devices and methods provide steady state sampling. However, a need exists for transient sampling.
The prior art bagged mini diluter is a proportional sampler but the volume that it draws is too small. Also, it dilutes the sample before it is collected which is not desirable when measuring PAHs from modern spark ignited engines due to the low concentration of PAHs in their exhaust.
Particulate matter (PM) samplers also pull a proportional sample but, if pulling from a Constant Volume System (CVS), the flow to which that sample is proportional, is very steady. While PM samplers that pull from exhaust which varies in flow rate are also known, the volume that such samplers pull out is too small.